Aspects of the present disclosure relate generally to cables, such as fiber optic cables that may support and carry optical fibers as well as other cable components. More specifically, aspects of the present disclosure relate to a film for binding elements of a cable, such as buffer tubes wound around a central strength member in a core of a fiber optic cable.
Loose tube fiber optic cables typically use crisscrossing binder yarns that are counter-helically wrapped about a core of the cable to constrain stranded buffer tubes containing optical fibers, particularly with arrangements of the buffer tubes that include reverse-oscillatory winding patterns of the buffer tubes where the lay direction of the buffer tubes periodically reverses around a (straight) central strength member along the length of the core. The central strength member is typically a rod of a rigid material. Buffer tubes are typically cylindrical tubes (generally 2 to 3 mm in outer diameter) that contain optical fibers. Open space in the interior of a buffer tube may be water-blocked with grease. Other types of conventional cables and cable components may use binder yarns, such as bundles of micromodules and tight-buffered fibers.
Applicants have found that stranded buffer tubes and other such cable components, particularly those stranded in a reverse-oscillating pattern, function as a loaded dual-torsion spring with bias to unwind and correspondingly stretch out along the length of the cable. The binder yarns constrain the stranded components in the reversals. However, binder yarns may impart distortions or stress concentrations in the stranded components, where the binder yarns pass over the respective components, potentially resulting in attenuation of optical fibers therein. The level of attenuation is a function of the tension in the binder yarns, which itself may be a function of the number, arrangement, structure, and materials of the components, among other variables. A need exists for a binder system that allows for faster manufacturing of cables, reduces potential for attenuation of optical fibers in the cables, such as by avoiding point loading of stranded components, and/or allows for long, continuous lengths of such cables to be efficiently manufactured.